Mathematical location models have been increasingly applied in the health services at the international level. In Brazil, although incipient, there exists an enormous potential for the use of such models in the area of public health. In this paper several location models that can be applied to public health are presented initially, and the location of non-emergency services, of emergency services and of services hierarchically related are analysed. A hierarchical model is then applied to the location of maternal and perinatal assistance in the municipality of Rio de Janeiro. In this part, after presenting some related data for the municipality, a four-level hierarchical model (location of out-patient units, maternity hospitals, neonatal hospitals and general hospitals) is proposed and the impact that the adoption of this methodology would have as compared with that of the present system is analysed.